Impact of Hypothermic Oxygenated Machine Perfusion on Immune Cell Clearance in Liver Transplantation: Enhancing Graft Function and Post-Transplant Outcomes

<b>Background:</b> Hypothermic oxygenated machine perfusion (HOPE) has emerged as a critical innovation in liver transplantation (LTx), offering significant protection against ischemia-reperfusion injury (IRI). This study focuses on quantifying and characterizing immune cells flushed out during HOPE to explore its effects on graft function and post-transplant outcomes. <b>Materials and Methods:</b> Fifty liver grafts underwent end-ischemic HOPE. Perfusate samples were collected at three time points: at the start of perfusion, after 10 min, and at the end of perfusion. The samples were analyzed to quantify and characterize immune cells, assessing the effectiveness of HOPE in reducing cellular debris and its impact on graft quality. <b>Results:</b> The primary perfusate contained significant concentrations of immune cells, mainly segmented neutrophils, lymphocytes, and monocytes. After 10 min of perfusion, outflow cell concentration decreased by over 95%, and by the end of perfusion, a more than 99% reduction was observed. <b>Conclusions:</b> HOPE effectively reduces immune cell concentrations in liver grafts, suggesting a mechanism for improved graft function and reduced post-transplant complications. These findings support the continued use and optimization of HOPE in LTx.